An alternative approach is to go with an awning and awning tent kit; this provides lots of flexibility as an awning is always great when the weather is really good or bad and on special occasions it can be quickly converted into a tent but then the vehicle is stuck as a tent base. As schira-ki found out, the annexes are designed to be around 6' plus in height to make a room; less than this, the bottom bunches up, looks awful and does not stake down; very important if the weather is windy.